NOVRAM
The NOVRAM can be used to reliably save important variable values, such as production data or counter values, in the event of a power failure. The memory size of the NOVRAM is limited and only suitable for smaller data quantities up to 4 kB.
In this chapter we show you how the NOVRAM is used in TwinCAT 3.
Functioning
The NOVRAM (Non-Volatile Random Access Memory) is a special memory component that is used to reliably save important data. The NOVRAM consists of two sections, a volatile memory and a non-volatile memory.
TwinCAT only writes to the volatile section of the NOVRAM. In the event of a power failure, the data are automatically copied from the volatile memory into the non-volatile memory. The energy required for this process is supplied by a capacitor. As soon as the power supply is restored, the data are automatically copied back into the volatile memory, so that TwinCAT can continue to use them.
Memory size
The NOVRAM has a capacity of 4 kB. The data are saved cyclically and alternately based on the dual buffer principle, in order to avoid the risk of data inconsistency.
Requirements
Development environment | Target platforms | Hardware | PLC libraries |
|---|---|---|---|
TwinCAT 3.1 Build: 4020 | PC or CX (x86, x64, ARM) | CX70xx, CX9020, CX20x0, CX20x2, CX20x3 | Tc2_IoFunctions |